Noise reduction is practiced in the art using dark fixed pattern subtraction as in U.S. Pat. No. 6,424,375, here an electronic circuit is used to remove dark fixed pattern noise by electronically adjusting pixel responses to align them to an aim response. U.S. Pat. No. 6,418,241 discloses a system in which column biases are corrected after measuring the average of each column and adjusting each column to some aim bias. The Canon D30 digital camera also apparently performs dark captures with the shutter closed in order to obtain an estimate of the sensor's dark frame response. The invention described here offers significant improvement over the apparently simple concurrent dark frame capture, as described in the prior art. 1) This invention describes dark fixed pattern correction that has been optimized to correct dark the fixed pattern associated with a range of the operational conditions of integration time and 2) It describes pixel response non-uniformity correction which has been optimized for a range of the operational conditions of imager integration time and imager temperature. 3) It also describes an alternate measure of the operational conditions to be used to adjust both the dark fixed pattern map and the pixel response non-uniformity. Here the dark pixels of the imager are averaged and used as means of adjusting the dark fixed pattern and pixel response non-uniformity.